tappsa 2010 influence of enzymes on refining of eucalyptus pulps crystal steel francois wolfaardt
TRANSCRIPT
TAPPSA 2010
Influence of enzymes on refining of eucalyptus pulps
Crystal SteelFrancois Wolfaardt
Technology Centre
Aim
Improve the refining of Eucalyptus grandis and E. nitens
pulps using cellulases & hemicellulases
Technology Centre
Why Eucalyptus grandis and E. nitens?
Slide 4Slide 4
Eucalyptus grandisTraditional wood timer sourceExpansion of pulp & paper industry increased need for more land, which were at higher altitudes
E. nitens was grown due to cold tolerance
Eucalyptus nitens Grows fast & adaptableGood quality fibreSmaller fibres & thinner cell wallsHigh tensile, bulk density, opacity and brightness
Technology Centre
Introduction: Refining of wood pulp fibres
Refining pulp fibres
Fibrillation & fines
Fibre swelling De-curling
Cutting
Reduced fibre lengthIncreased effective length & sheet formation
Increased bonding & strength of fibres
Improved bonding & reduced pulp freeness
Technology Centre
Introduction: Enzymes
Hemicellulase Xylanase (X) (HW)
CellulasesEndoglucanase (EG)
Cellobiohydrolase (CBH)
Crystallinecellulose
Amorphouscellulose
No
n-red
ucin
g en
d
Red
uci
ng
en
d
CBHII CBHI
EG
Hemicellulose
X
Technology Centre
Refining with enzymes
1µm1µm
Hardwood pulp samples treated with endoglucanase on commercial scale with refining.
Untreated Treated
Technology Centre
Introduction: Refining with enzymes
Enzyme refining of pulp fibres
Fibrillation & fines ?
Fibre swelling ? De-curling ?
Cutting ?
Technology CentreSlide 9
Method: Pilot scale refining
3% pulp consistency Enzymes: 0.02g protein/ kg pulp
Endoglucanase, Cellobiohydrolase & Xylanase
Sample before incubation, at 20 min & at each refining energy:
E. grandis 24.9, 49.2, 73.1, 96.5 & 119.4 kWh/t
E. nitens 21.5, 42.3, 62.6, 82.2 & 101.3 kWh/t
Technology CentreSlide 10
Method: Sample analysis
PulpFreeness (CSF)Water retention value (WRV)
PaperTensile strengthTear strengthBulk densityPorosity
20 cm
Technology Centre
Results : E. grandis & E. nitens refining curves
0
100
200
300
400
500
600
0 20 40 60 80 100 120
Energy (kWh/t)
Fre
enes
s (m
l CS
F)
Control CBH Xylanase EG
0 20 40 60 80 100
Energy (kWh/t)
E. grandis E. nitens
Technology Centre
Results and Discussion
-100
-50
0
50
100
150
Energy CSF WRV Tear Tensile Bulk Porosity
Re
lative
ch
an
ge
(%
)
Control @ 450 ml
Technology Centre
Results: Xylanase
Technology Centre
Results: Xylanase
-100
-50
0
50
100
150
Energy CSF WRV Tear Tensile Bulk Porosity
Re
lative
ch
an
ge
(%
)
E. grandis E. nitens
Technology Centre
Results: Endoglucanase
Technology Centre
Results: Endoglucanase
-100
-50
0
50
100
150
Energy CSF WRV Tear Tensile Bulk Porosity
Re
lative
ch
an
ge
(%
)
E. grandis E. nitens
Technology Centre
Results: Cellobiohydrolase
Technology Centre
Results: Cellobiohydrolase
-100
-50
0
50
100
150
Energy CSF WRV Tear Tensile Bulk Porosity
Re
lative
ch
an
ge
(%
)
E. grandis E. nitens
?
Technology Centre
Conclusions
Enzymes affected properties in a similar way on the two HW species
Most noted change with enzymes were:
Xylanase on E. nitens with a 75% reduction in porosity
EG on E. grandis with a 50% improvement in tensile
CBH on E. grandis with 12% increase in tear and 20% increase in tensile
The enzymes have better improvements on E. grandis than E. nitens
Technology Centre
General Conclusion
Enzymes do improve pulp propertiesHOWEVER
Enzymes are specific in their activity on different pulps Specific properties need to be targeted possibly at the
expense of others
Technology Centre
Acknowledgements
Sappi Manufacturing UKZN – EM Unit Genencor, Novozymes and AB Enzymes